security/selinux/netlabel.c

   1 /*
   2  * SELinux NetLabel Support
   3  *
   4  * This file provides the necessary glue to tie NetLabel into the SELinux
   5  * subsystem.
   6  *
   7  * Author: Paul Moore <paul@paul-moore.com>
   8  *
   9  */
  10
  11 /*
  12  * (c) Copyright Hewlett-Packard Development Company, L.P., 2007, 2008
  13  *
  14  * This program is free software;  you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License as published by
  16  * the Free Software Foundation; either version 2 of the License, or
  17  * (at your option) any later version.
  18  *
  19  * This program is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY;  without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
  22  * the GNU General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  26  *
  27  */
  28
  29 #include <linux/spinlock.h>
  30 #include <linux/rcupdate.h>
  31 #include <linux/gfp.h>
  32 #include <linux/ip.h>
  33 #include <linux/ipv6.h>
  34 #include <net/sock.h>
  35 #include <net/netlabel.h>
  36 #include <net/ip.h>
  37 #include <net/ipv6.h>
  38
  39 #include "objsec.h"
  40 #include "security.h"
  41 #include "netlabel.h"
  42
  43 /**
  44  * selinux_netlbl_sidlookup_cached - Cache a SID lookup
  45  * @skb: the packet
  46  * @secattr: the NetLabel security attributes
  47  * @sid: the SID
  48  *
  49  * Description:
  50  * Query the SELinux security server to lookup the correct SID for the given
  51  * security attributes.  If the query is successful, cache the result to speed
  52  * up future lookups.  Returns zero on success, negative values on failure.
  53  *
  54  */
  55 static int selinux_netlbl_sidlookup_cached(struct sk_buff *skb,
  56                                            u16 family,
  57                                            struct netlbl_lsm_secattr *secattr,
  58                                            u32 *sid)
  59 {
  60         int rc;
  61
  62         rc = security_netlbl_secattr_to_sid(&selinux_state, secattr, sid);
  63         if (rc == 0 &&
  64             (secattr->flags & NETLBL_SECATTR_CACHEABLE) &&
  65             (secattr->flags & NETLBL_SECATTR_CACHE))
  66                 netlbl_cache_add(skb, family, secattr);
  67
  68         return rc;
  69 }
  70
  71 /**
  72  * selinux_netlbl_sock_genattr - Generate the NetLabel socket secattr
  73  * @sk: the socket
  74  *
  75  * Description:
  76  * Generate the NetLabel security attributes for a socket, making full use of
  77  * the socket's attribute cache.  Returns a pointer to the security attributes
  78  * on success, NULL on failure.
  79  *
  80  */
  81 static struct netlbl_lsm_secattr *selinux_netlbl_sock_genattr(struct sock *sk)
  82 {
  83         int rc;
  84         struct sk_security_struct *sksec = sk->sk_security;
  85         struct netlbl_lsm_secattr *secattr;
  86
  87         if (sksec->nlbl_secattr != NULL)
  88                 return sksec->nlbl_secattr;
  89
  90         secattr = netlbl_secattr_alloc(GFP_ATOMIC);
  91         if (secattr == NULL)
  92                 return NULL;
  93         rc = security_netlbl_sid_to_secattr(&selinux_state, sksec->sid,
  94                                             secattr);
  95         if (rc != 0) {
  96                 netlbl_secattr_free(secattr);
  97                 return NULL;
  98         }
  99         sksec->nlbl_secattr = secattr;
 100
 101         return secattr;
 102 }
 103
 104 /**
 105  * selinux_netlbl_sock_getattr - Get the cached NetLabel secattr
 106  * @sk: the socket
 107  * @sid: the SID
 108  *
 109  * Query the socket's cached secattr and if the SID matches the cached value
 110  * return the cache, otherwise return NULL.
 111  *
 112  */
 113 static struct netlbl_lsm_secattr *selinux_netlbl_sock_getattr(
 114                                                         const struct sock *sk,
 115                                                         u32 sid)
 116 {
 117         struct sk_security_struct *sksec = sk->sk_security;
 118         struct netlbl_lsm_secattr *secattr = sksec->nlbl_secattr;
 119
 120         if (secattr == NULL)
 121                 return NULL;
 122
 123         if ((secattr->flags & NETLBL_SECATTR_SECID) &&
 124             (secattr->attr.secid == sid))
 125                 return secattr;
 126
 127         return NULL;
 128 }
 129
 130 /**
 131  * selinux_netlbl_cache_invalidate - Invalidate the NetLabel cache
 132  *
 133  * Description:
 134  * Invalidate the NetLabel security attribute mapping cache.
 135  *
 136  */
 137 void selinux_netlbl_cache_invalidate(void)
 138 {
 139         netlbl_cache_invalidate();
 140 }
 141
 142 /**
 143  * selinux_netlbl_err - Handle a NetLabel packet error
 144  * @skb: the packet
 145  * @error: the error code
 146  * @gateway: true if host is acting as a gateway, false otherwise
 147  *
 148  * Description:
 149  * When a packet is dropped due to a call to avc_has_perm() pass the error
 150  * code to the NetLabel subsystem so any protocol specific processing can be
 151  * done.  This is safe to call even if you are unsure if NetLabel labeling is
 152  * present on the packet, NetLabel is smart enough to only act when it should.
 153  *
 154  */
 155 void selinux_netlbl_err(struct sk_buff *skb, u16 family, int error, int gateway)
 156 {
 157         netlbl_skbuff_err(skb, family, error, gateway);
 158 }
 159
 160 /**
 161  * selinux_netlbl_sk_security_free - Free the NetLabel fields
 162  * @sksec: the sk_security_struct
 163  *
 164  * Description:
 165  * Free all of the memory in the NetLabel fields of a sk_security_struct.
 166  *
 167  */
 168 void selinux_netlbl_sk_security_free(struct sk_security_struct *sksec)
 169 {
 170         if (sksec->nlbl_secattr != NULL)
 171                 netlbl_secattr_free(sksec->nlbl_secattr);
 172 }
 173
 174 /**
 175  * selinux_netlbl_sk_security_reset - Reset the NetLabel fields
 176  * @sksec: the sk_security_struct
 177  * @family: the socket family
 178  *
 179  * Description:
 180  * Called when the NetLabel state of a sk_security_struct needs to be reset.
 181  * The caller is responsible for all the NetLabel sk_security_struct locking.
 182  *
 183  */
 184 void selinux_netlbl_sk_security_reset(struct sk_security_struct *sksec)
 185 {
 186         sksec->nlbl_state = NLBL_UNSET;
 187 }
 188
 189 /**
 190  * selinux_netlbl_skbuff_getsid - Get the sid of a packet using NetLabel
 191  * @skb: the packet
 192  * @family: protocol family
 193  * @type: NetLabel labeling protocol type
 194  * @sid: the SID
 195  *
 196  * Description:
 197  * Call the NetLabel mechanism to get the security attributes of the given
 198  * packet and use those attributes to determine the correct context/SID to
 199  * assign to the packet.  Returns zero on success, negative values on failure.
 200  *
 201  */
 202 int selinux_netlbl_skbuff_getsid(struct sk_buff *skb,
 203                                  u16 family,
 204                                  u32 *type,
 205                                  u32 *sid)
 206 {
 207         int rc;
 208         struct netlbl_lsm_secattr secattr;
 209
 210         if (!netlbl_enabled()) {
 211                 *sid = SECSID_NULL;
 212                 return 0;
 213         }
 214
 215         netlbl_secattr_init(&secattr);
 216         rc = netlbl_skbuff_getattr(skb, family, &secattr);
 217         if (rc == 0 && secattr.flags != NETLBL_SECATTR_NONE)
 218                 rc = selinux_netlbl_sidlookup_cached(skb, family,
 219                                                      &secattr, sid);
 220         else
 221                 *sid = SECSID_NULL;
 222         *type = secattr.type;
 223         netlbl_secattr_destroy(&secattr);
 224
 225         return rc;
 226 }
 227
 228 /**
 229  * selinux_netlbl_skbuff_setsid - Set the NetLabel on a packet given a sid
 230  * @skb: the packet
 231  * @family: protocol family
 232  * @sid: the SID
 233  *
 234  * Description
 235  * Call the NetLabel mechanism to set the label of a packet using @sid.
 236  * Returns zero on success, negative values on failure.
 237  *
 238  */
 239 int selinux_netlbl_skbuff_setsid(struct sk_buff *skb,
 240                                  u16 family,
 241                                  u32 sid)
 242 {
 243         int rc;
 244         struct netlbl_lsm_secattr secattr_storage;
 245         struct netlbl_lsm_secattr *secattr = NULL;
 246         struct sock *sk;
 247
 248         /* if this is a locally generated packet check to see if it is already
 249          * being labeled by it's parent socket, if it is just exit */
 250         sk = skb_to_full_sk(skb);
 251         if (sk != NULL) {
 252                 struct sk_security_struct *sksec = sk->sk_security;
 253
 254                 if (sksec->nlbl_state != NLBL_REQSKB)
 255                         return 0;
 256                 secattr = selinux_netlbl_sock_getattr(sk, sid);
 257         }
 258         if (secattr == NULL) {
 259                 secattr = &secattr_storage;
 260                 netlbl_secattr_init(secattr);
 261                 rc = security_netlbl_sid_to_secattr(&selinux_state, sid,
 262                                                     secattr);
 263                 if (rc != 0)
 264                         goto skbuff_setsid_return;
 265         }
 266
 267         rc = netlbl_skbuff_setattr(skb, family, secattr);
 268
 269 skbuff_setsid_return:
 270         if (secattr == &secattr_storage)
 271                 netlbl_secattr_destroy(secattr);
 272         return rc;
 273 }
 274
 275 /**
 276  * selinux_netlbl_sctp_assoc_request - Label an incoming sctp association.
 277  * @ep: incoming association endpoint.
 278  * @skb: the packet.
 279  *
 280  * Description:
 281  * A new incoming connection is represented by @ep, ......
 282  * Returns zero on success, negative values on failure.
 283  *
 284  */
 285 int selinux_netlbl_sctp_assoc_request(struct sctp_endpoint *ep,
 286                                      struct sk_buff *skb)
 287 {
 288         int rc;
 289         struct netlbl_lsm_secattr secattr;
 290         struct sk_security_struct *sksec = ep->base.sk->sk_security;
 291         struct sockaddr *addr;
 292         struct sockaddr_in addr4;
 293 #if IS_ENABLED(CONFIG_IPV6)
 294         struct sockaddr_in6 addr6;
 295 #endif
 296
 297         if (ep->base.sk->sk_family != PF_INET &&
 298                                 ep->base.sk->sk_family != PF_INET6)
 299                 return 0;
 300
 301         netlbl_secattr_init(&secattr);
 302         rc = security_netlbl_sid_to_secattr(&selinux_state,
 303                                             ep->secid, &secattr);
 304         if (rc != 0)
 305                 goto assoc_request_return;
 306
 307         /* Move skb hdr address info to a struct sockaddr and then call
 308          * netlbl_conn_setattr().
 309          */
 310         if (ip_hdr(skb)->version == 4) {
 311                 addr4.sin_family = AF_INET;
 312                 addr4.sin_addr.s_addr = ip_hdr(skb)->saddr;
 313                 addr = (struct sockaddr *)&addr4;
 314 #if IS_ENABLED(CONFIG_IPV6)
 315         } else {
 316                 addr6.sin6_family = AF_INET6;
 317                 addr6.sin6_addr = ipv6_hdr(skb)->saddr;
 318                 addr = (struct sockaddr *)&addr6;
 319 #endif
 320         }
 321
 322         rc = netlbl_conn_setattr(ep->base.sk, addr, &secattr);
 323         if (rc == 0)
 324                 sksec->nlbl_state = NLBL_LABELED;
 325
 326 assoc_request_return:
 327         netlbl_secattr_destroy(&secattr);
 328         return rc;
 329 }
 330
 331 /**
 332  * selinux_netlbl_inet_conn_request - Label an incoming stream connection
 333  * @req: incoming connection request socket
 334  *
 335  * Description:
 336  * A new incoming connection request is represented by @req, we need to label
 337  * the new request_sock here and the stack will ensure the on-the-wire label
 338  * will get preserved when a full sock is created once the connection handshake
 339  * is complete.  Returns zero on success, negative values on failure.
 340  *
 341  */
 342 int selinux_netlbl_inet_conn_request(struct request_sock *req, u16 family)
 343 {
 344         int rc;
 345         struct netlbl_lsm_secattr secattr;
 346
 347         if (family != PF_INET && family != PF_INET6)
 348                 return 0;
 349
 350         netlbl_secattr_init(&secattr);
 351         rc = security_netlbl_sid_to_secattr(&selinux_state, req->secid,
 352                                             &secattr);
 353         if (rc != 0)
 354                 goto inet_conn_request_return;
 355         rc = netlbl_req_setattr(req, &secattr);
 356 inet_conn_request_return:
 357         netlbl_secattr_destroy(&secattr);
 358         return rc;
 359 }
 360
 361 /**
 362  * selinux_netlbl_inet_csk_clone - Initialize the newly created sock
 363  * @sk: the new sock
 364  *
 365  * Description:
 366  * A new connection has been established using @sk, we've already labeled the
 367  * socket via the request_sock struct in selinux_netlbl_inet_conn_request() but
 368  * we need to set the NetLabel state here since we now have a sock structure.
 369  *
 370  */
 371 void selinux_netlbl_inet_csk_clone(struct sock *sk, u16 family)
 372 {
 373         struct sk_security_struct *sksec = sk->sk_security;
 374
 375         if (family == PF_INET)
 376                 sksec->nlbl_state = NLBL_LABELED;
 377         else
 378                 sksec->nlbl_state = NLBL_UNSET;
 379 }
 380
 381 /**
 382  * selinux_netlbl_sctp_sk_clone - Copy state to the newly created sock
 383  * @sk: current sock
 384  * @newsk: the new sock
 385  *
 386  * Description:
 387  * Called whenever a new socket is created by accept(2) or sctp_peeloff(3).
 388  */
 389 void selinux_netlbl_sctp_sk_clone(struct sock *sk, struct sock *newsk)
 390 {
 391         struct sk_security_struct *sksec = sk->sk_security;
 392         struct sk_security_struct *newsksec = newsk->sk_security;
 393
 394         newsksec->nlbl_state = sksec->nlbl_state;
 395 }
 396
 397 /**
 398  * selinux_netlbl_socket_post_create - Label a socket using NetLabel
 399  * @sock: the socket to label
 400  * @family: protocol family
 401  *
 402  * Description:
 403  * Attempt to label a socket using the NetLabel mechanism using the given
 404  * SID.  Returns zero values on success, negative values on failure.
 405  *
 406  */
 407 int selinux_netlbl_socket_post_create(struct sock *sk, u16 family)
 408 {
 409         int rc;
 410         struct sk_security_struct *sksec = sk->sk_security;
 411         struct netlbl_lsm_secattr *secattr;
 412
 413         if (family != PF_INET && family != PF_INET6)
 414                 return 0;
 415
 416         secattr = selinux_netlbl_sock_genattr(sk);
 417         if (secattr == NULL)
 418                 return -ENOMEM;
 419         rc = netlbl_sock_setattr(sk, family, secattr);
 420         switch (rc) {
 421         case 0:
 422                 sksec->nlbl_state = NLBL_LABELED;
 423                 break;
 424         case -EDESTADDRREQ:
 425                 sksec->nlbl_state = NLBL_REQSKB;
 426                 rc = 0;
 427                 break;
 428         }
 429
 430         return rc;
 431 }
 432
 433 /**
 434  * selinux_netlbl_sock_rcv_skb - Do an inbound access check using NetLabel
 435  * @sksec: the sock's sk_security_struct
 436  * @skb: the packet
 437  * @family: protocol family
 438  * @ad: the audit data
 439  *
 440  * Description:
 441  * Fetch the NetLabel security attributes from @skb and perform an access check
 442  * against the receiving socket.  Returns zero on success, negative values on
 443  * error.
 444  *
 445  */
 446 int selinux_netlbl_sock_rcv_skb(struct sk_security_struct *sksec,
 447                                 struct sk_buff *skb,
 448                                 u16 family,
 449                                 struct common_audit_data *ad)
 450 {
 451         int rc;
 452         u32 nlbl_sid;
 453         u32 perm;
 454         struct netlbl_lsm_secattr secattr;
 455
 456         if (!netlbl_enabled())
 457                 return 0;
 458
 459         netlbl_secattr_init(&secattr);
 460         rc = netlbl_skbuff_getattr(skb, family, &secattr);
 461         if (rc == 0 && secattr.flags != NETLBL_SECATTR_NONE)
 462                 rc = selinux_netlbl_sidlookup_cached(skb, family,
 463                                                      &secattr, &nlbl_sid);
 464         else
 465                 nlbl_sid = SECINITSID_UNLABELED;
 466         netlbl_secattr_destroy(&secattr);
 467         if (rc != 0)
 468                 return rc;
 469
 470         switch (sksec->sclass) {
 471         case SECCLASS_UDP_SOCKET:
 472                 perm = UDP_SOCKET__RECVFROM;
 473                 break;
 474         case SECCLASS_TCP_SOCKET:
 475                 perm = TCP_SOCKET__RECVFROM;
 476                 break;
 477         default:
 478                 perm = RAWIP_SOCKET__RECVFROM;
 479         }
 480
 481         rc = avc_has_perm(&selinux_state,
 482                           sksec->sid, nlbl_sid, sksec->sclass, perm, ad);
 483         if (rc == 0)
 484                 return 0;
 485
 486         if (nlbl_sid != SECINITSID_UNLABELED)
 487                 netlbl_skbuff_err(skb, family, rc, 0);
 488         return rc;
 489 }
 490
 491 /**
 492  * selinux_netlbl_option - Is this a NetLabel option
 493  * @level: the socket level or protocol
 494  * @optname: the socket option name
 495  *
 496  * Description:
 497  * Returns true if @level and @optname refer to a NetLabel option.
 498  * Helper for selinux_netlbl_socket_setsockopt().
 499  */
 500 static inline int selinux_netlbl_option(int level, int optname)
 501 {
 502         return (level == IPPROTO_IP && optname == IP_OPTIONS) ||
 503                 (level == IPPROTO_IPV6 && optname == IPV6_HOPOPTS);
 504 }
 505
 506 /**
 507  * selinux_netlbl_socket_setsockopt - Do not allow users to remove a NetLabel
 508  * @sock: the socket
 509  * @level: the socket level or protocol
 510  * @optname: the socket option name
 511  *
 512  * Description:
 513  * Check the setsockopt() call and if the user is trying to replace the IP
 514  * options on a socket and a NetLabel is in place for the socket deny the
 515  * access; otherwise allow the access.  Returns zero when the access is
 516  * allowed, -EACCES when denied, and other negative values on error.
 517  *
 518  */
 519 int selinux_netlbl_socket_setsockopt(struct socket *sock,
 520                                      int level,
 521                                      int optname)
 522 {
 523         int rc = 0;
 524         struct sock *sk = sock->sk;
 525         struct sk_security_struct *sksec = sk->sk_security;
 526         struct netlbl_lsm_secattr secattr;
 527
 528         if (selinux_netlbl_option(level, optname) &&
 529             (sksec->nlbl_state == NLBL_LABELED ||
 530              sksec->nlbl_state == NLBL_CONNLABELED)) {
 531                 netlbl_secattr_init(&secattr);
 532                 lock_sock(sk);
 533                 /* call the netlabel function directly as we want to see the
 534                  * on-the-wire label that is assigned via the socket's options
 535                  * and not the cached netlabel/lsm attributes */
 536                 rc = netlbl_sock_getattr(sk, &secattr);
 537                 release_sock(sk);
 538                 if (rc == 0)
 539                         rc = -EACCES;
 540                 else if (rc == -ENOMSG)
 541                         rc = 0;
 542                 netlbl_secattr_destroy(&secattr);
 543         }
 544
 545         return rc;
 546 }
 547
 548 /**
 549  * selinux_netlbl_socket_connect_helper - Help label a client-side socket on
 550  * connect
 551  * @sk: the socket to label
 552  * @addr: the destination address
 553  *
 554  * Description:
 555  * Attempt to label a connected socket with NetLabel using the given address.
 556  * Returns zero values on success, negative values on failure.
 557  *
 558  */
 559 static int selinux_netlbl_socket_connect_helper(struct sock *sk,
 560                                                 struct sockaddr *addr)
 561 {
 562         int rc;
 563         struct sk_security_struct *sksec = sk->sk_security;
 564         struct netlbl_lsm_secattr *secattr;
 565
 566         /* connected sockets are allowed to disconnect when the address family
 567          * is set to AF_UNSPEC, if that is what is happening we want to reset
 568          * the socket */
 569         if (addr->sa_family == AF_UNSPEC) {
 570                 netlbl_sock_delattr(sk);
 571                 sksec->nlbl_state = NLBL_REQSKB;
 572                 rc = 0;
 573                 return rc;
 574         }
 575         secattr = selinux_netlbl_sock_genattr(sk);
 576         if (secattr == NULL) {
 577                 rc = -ENOMEM;
 578                 return rc;
 579         }
 580         rc = netlbl_conn_setattr(sk, addr, secattr);
 581         if (rc == 0)
 582                 sksec->nlbl_state = NLBL_CONNLABELED;
 583
 584         return rc;
 585 }
 586
 587 /**
 588  * selinux_netlbl_socket_connect_locked - Label a client-side socket on
 589  * connect
 590  * @sk: the socket to label
 591  * @addr: the destination address
 592  *
 593  * Description:
 594  * Attempt to label a connected socket that already has the socket locked
 595  * with NetLabel using the given address.
 596  * Returns zero values on success, negative values on failure.
 597  *
 598  */
 599 int selinux_netlbl_socket_connect_locked(struct sock *sk,
 600                                          struct sockaddr *addr)
 601 {
 602         struct sk_security_struct *sksec = sk->sk_security;
 603
 604         if (sksec->nlbl_state != NLBL_REQSKB &&
 605             sksec->nlbl_state != NLBL_CONNLABELED)
 606                 return 0;
 607
 608         return selinux_netlbl_socket_connect_helper(sk, addr);
 609 }
 610
 611 /**
 612  * selinux_netlbl_socket_connect - Label a client-side socket on connect
 613  * @sk: the socket to label
 614  * @addr: the destination address
 615  *
 616  * Description:
 617  * Attempt to label a connected socket with NetLabel using the given address.
 618  * Returns zero values on success, negative values on failure.
 619  *
 620  */
 621 int selinux_netlbl_socket_connect(struct sock *sk, struct sockaddr *addr)
 622 {
 623         int rc;
 624
 625         lock_sock(sk);
 626         rc = selinux_netlbl_socket_connect_locked(sk, addr);
 627         release_sock(sk);
 628
 629         return rc;
 630 }